Control device for compressed-air brakes

ABSTRACT

The invention relates to a control device for compressed-air brakes having a control valve, comprising a housing, a piston rod, a piston, a second piston, a double-seat valve, having a control element, having a supply air reservoir, having a control chamber, having a main air pipe; one side of the piston being connected in a compressed-air carrying manner with the main air pipe; the other side of the piston being connected in a compressed-air carrying manner with the control chamber; one side of the second piston having a compressed-air connection to a brake cylinder or a brake cylinder pilot chamber; the double-seat valve being connected between a compressed-air connection of the supply air reservoir and the compressed-air connection to the brake cylinder or to the brake cylinder pilot chamber.  
     The invention is characterized by the following features:  
     A compressed-air connection from the main air pipe to the double-seat valve is connected parallel to the compressed-air connection from the supply air reservoir;  
     a valve comprising a piston rod and a piston is connected into the parallel compressed-air connection;  
     on one side, the piston has a compressed-air connection device for a control pressure;  
     on the other side, the piston has a device for generating a counterforce, particularly a pressure spring;  
     a control element is connected into the connection point between the main air pipe, the control chamber, the compressed-air connection device for the control pressure, the brake cylinder or the brake cylinder pilot space and the environment.

[0001] The invention relates to a control device for compressed-airbrakes according to the preamble of claim 1.

[0002] Compressed-air brakes are used, for example, in the case of railvehicles, where the braking operation is initiated by lowering thepressure in a main air pipe. This is provided for safety reasons butmeans that a control device is required which ensures that, when thepressure is lowered in the main air pipe, a pressure rise takes place inthe brake cylinders. Such a control device is described, for example, inEuropean Patent Document EP 0 133 653 B1.

[0003] Because of their complexity, such control devices should have acertain size. As illustrated, for example, in Specification B-EC00.25,Picture 5 and 6, a control sleeve 101.37, a minimum pressure limitingdevice F and a Ü-monitor U with the Ü-chamber K are provided. These arethree structural components which together represent certainconstructional expenditures, particularly the position of the controlsleeve in the piston rod of the triple-pressure element G influencingthe size of the overall control valve. The influence is caused, on theone hand, directly by the size of the control sleeve which has an effecton the height of the housing, but also indirectly because, for operatingthe control sleeve and overcoming the friction of the sliding sealingcaused by the control sleeve, a certain size of the diaphragm disk101.21 is required.

[0004] It is an object of the invention to provide a control device atreduced expenditures and of a smaller size. Furthermore, when automaticbrakes are used, a braking of all cars which is as simultaneous anduniform as possible is to be achieved by means of the control device.

[0005] According to the invention, this object is achieved by means of adevice having the characteristics of claim 1. Additional advantageousembodiments of a control device further developed according to theinvention are described in the dependent claims.

[0006] The idea on which the invention is based is that of omitting oneof the three structural components—the control sleeve, the minimumpressure limiting device and the Ü-monitor without—reducingfunctionality. The reason is that the control sleeve surprisinglybecomes superfluous when the main air pipe is successfully connected ina meaningfully time-controlled manner to valve V 101.2. The control ofthis connection takes place by a valve whose position correspondsapproximately to the minimal pressure limiting device F. An especiallyconstructed control element is required which combines in itself thefunction of the Ü-monitor and of the A-monitor D of the known controldevice.

[0007] As a result, the size can be reduced by approximately 50% incomparison to the known control device while the hysteresis of thedevice does not exceed the normal value.

[0008] According to the invention, the control device is equipped with acontrol valve which, in a housing, comprises a piston rod with twopistons and a double-seat valve. Furthermore, the invention comprisesthe above-mentioned control element, a supply air reservoir, a controlchamber and a main air pipe. One side of the first piston is connectedwith the main air pipe in a compressed-air carrying manner, and theother side is connected with the control chamber in a compressed-aircarrying manner. On its one side, the second piston is connected in acompressed-air carrying manner with a brake cylinder pilot chamber,while an ambient pressure exists on the other side. In this case, theconstruction according to the invention is not limited to the wiring toa brake cylinder pilot chamber but corresponding compressed-air guidingconnections directly with a brake cylinder are also conceivable. Thedouble-seat valve is connected between a compressed-air connection tothe supply air reservoir and a compressed-air connection to the brakecylinder pilot chamber. A compressed-air connection is connectedparallel to the compressed-air connection from the supply air reservoirto the double-seat valve, which compressed-air connection has theabove-mentioned valve which, in turn, comprises a piston rod and apiston. On one side, the piston has a compressed-air connection for acontrol pressure and, on the other side, a device is provided forgenerating a counterforce, preferably in the form of a pressure spring.

[0009] A control element is connected in the compressed-air carryingconnection point between the main air pipe, the control chamber, thecompressed-air connection for the control pressure, the brake cylinderpilot chamber and the environment.

[0010] The second piston of the double-seat valve is connected on itssecond side with the environment such that, in the case of a lowerposition of the piston rod with the two pistons, the brake cylinderchamber is vented by way of the ambient connection. In this case, inthis lower position, the double-seat valve is advantageously closed sothat the compressed-air connection of the connection pipe from thesupply air reservoir to the double-seat valve—or the pipe connectedparallel thereto—is separated from the brake cylinder pilot chamber. Inan upper position of the piston rod with the two pistons, thedouble-seat valve is opened; the brake cylinder pilot chamber isseparated from the environment by the second piston, so that compressedair can flow by way of the double-seat valve into the brake cylinderpilot chamber.

[0011] Advantageously, the double-seat valve is constructed as a tappetvalve and is loaded in the closing direction by means of a pressurespring and in the opening direction by means of the piston rod of thecontrol valve. In another advantageous embodiment of the invention, theabove-described valve, which controls the connection between the mainair pipe and the double-seat valve, is constructed as a tappet valve.Advantageously, this tappet valve can also be loaded by means ofpressure spring in the closing direction and by means of the piston rodby means of the piston rod.

[0012] In an advantageous embodiment of the invention, theabove-described, especially constructed control element comprises apiston rod with an axial bore, a piston, a partition, a second partitionand a valve. In the piston rod, a bypass is constructed for bridging thepartition. On the side of the piston facing the valve, a compressed-airconnection to the brake cylinder pilot chamber is advantageouslyconstructed and, on the side of the piston facing away from the valve, adevice is arranged for generating a counterforce, advantageously in theform of a pressure spring. The compressed-air connection for the controlpressure can be connected by way of the valve with the main air pipe.The piston rod is arranged such that it leads from the valve through thetwo partitions to the piston. On the side of the partition facing thevalve, a connection is constructed for the compressed-air connectionwith the control pressure; on the side facing away from the valve, thecompressed-air connection is connected to the control chamber. Thecompressed-air connection to the brake cylinder pilot chamber isseparated by the second partition from the compressed-air connection tothe control chamber.

[0013] Particularly advantageously, the valve is also constructed hereas a tappet valve which is loaded in the closing direction by means of apressure spring and in the opening direction by means of the piston rod.

[0014] In an advantageous embodiment of the invention, the effect of thepressure build-up and of the pressure reduction respectively in thebrake cylinder pilot chamber can intensified in that a compressed-aircarrying connection to another valve—for the purpose of adifferentiation, in the following called a venting valve—is inserted inthe connection line between the control valve and the brake cylinderpilot chamber, which venting valve opens and closes with respect to theenvironment. In addition, the venting valve will open up the passage tothe environment when the brake cylinder pilot chamber by way of theambient connection in the control valve is vented at a lower position ofthe piston rod with the two pistons. Particularly advantageously, theventing valve is therefore also constructed as a tappet valve, is loadedat least indirectly in the opening direction by the control pressure andin the closing direction particularly by means of a pressure spring. Inthis case, the venting valve may essentially have the same constructionas the valve in the parallel pipe between the supply air reservoir andthe double seat valve respectively and the main air pipe, with apiston—loaded by the control pressure and on the other side by a devicefor generating a counterforce—and with a piston rod which, at acorrespondingly high control pressure, presses open the valve heldclosed particularly by the pressure spring and thus opens up theconnection of the brake cylinder pilot chamber to the environment.

[0015] Particularly advantageously, an additional valve and/or athrottle screen may also be connected into compressed-air connectionbetween the supply air reservoir and the double-seat valve. Furthermore,it is advantageous to construct the compressed-air connection from themain air pipe through the control element to the control chamber to haveparticular pressure losses, particularly as a result of the design ofthe bypass with a narrow flow cross-section. In addition, a valve and/ora throttle screen may advantageously be connected into thecompressed-air connection between the control element and the controlchamber. The advantages of the last-mentioned embodiments will bedescribed in the following in the description of a braking operation bymeans of an embodiment of the control device according to the invention.

[0016] The invention as well as the state of the art will be explainedin detail in the following by means of an embodiment and the attacheddrawings. Furthermore, the description of a braking operation is toclarify the method of operation of the device according to theinvention.

[0017]FIG. 1 is a view of a known control device with structuralcomponents according to Specification B-EC00.25, Picture 5 and 6;

[0018]FIG. 2 is a view of an embodiment of the control device accordingto the invention;

[0019]FIG. 3 is a view of an embodiment of the control elementillustrated in FIG. 2 as a black box;

[0020]FIG. 4 is a view of an embodiment of the control device accordingto the invention with an additional venting valve.

[0021]FIG. 2 illustrates the control valve with the housing 1 in which apiston rod 6, a first piston 3, a second piston 10 and a double-seatvalve 14 are arranged. One side of the piston 3 is connected by way of acompressed-air connection with the main air pipe 4; the other side isconnected by way of a compressed-air connection to the control chamber5. On its one side, the second piston 10 is connected by way of acompressed-air connection 24 with a brake cylinder pilot chamber 25. Theother side of the second piston 10 is connected by way of the bore 8with the environment. The adjacent pressure spaces of the pistons 3 and10 are separated by a partition 9 through which the piston rod 6 isguided by means of a sliding sealing device 28.

[0022] The double-seat valve 14 is loaded by the pressure spring 27 inthe closing direction and by the piston rod 6 in the opening direction.The side of the double-seat valve 14 facing away from the piston has aconnection device for a compressed-air connection 11 to the supply airreservoir 7. A valve 13 and a throttle 12 are connected into thiscompressed-air connection 11. A compressed-air connection 2 connectedparallel to the compressed-air connection 11 connects the valve 15 withthe double seat valve 14. The valve 15 is constructed as a tappet valveloaded in the closing direction by the pressure spring 34 and in theopening direction by the piston rod 35. The piston 16 arranged on theside of the piston rod 35 facing away from the valve is loaded by thepressure spring 18 on its side facing the valve; the other side isconnected with the compressed-air connection of the control pressure 17.In this case, the valve 15 is connected into the compressed-airconnection 2 from the main air pipe 4 to the double-seat valve 14.

[0023] The control element 30 is connected into the connection pointbetween the compressed-air pipes of the control chamber 5, the brakecylinder pilot chamber 25, the main air pipe 4, the compressed-airconnection of the control pressure 17 and the environment.

[0024] As illustrated in FIG. 3, the control element 30 has a piston rod29 with an axial bore 33 which is connected with a piston 2 on one sideand with a valve 19 on the other side. The valve 19, in turn, isconstructed as a tappet valve, loaded by a pressure spring 21 in theclosing direction and by the piston rod 29 in the opening direction. Onits side facing away from the valve, the piston 20 is loaded by apressure spring 22 and is acted upon by ambient pressure by way of abore.

[0025] By means of the valve 19, the partition 31, the second partition36 and the piston 20, the control element 30 is divided into fivepressure spaces. Each pressure space has a connection device for acompressed-air connection. Viewed in the axial direction from the valve19 to the piston, these are the connections to the main air pipe 4, tothe compressed-air connection device for the control pressure 17, to thecontrol chamber 5, to the brake cylinder pilot chamber 25 and to theenvironment. In a suitable position of the piston rod 29, a bypass 32 inthe piston rod 29 connects the pressure space ST—with the compressed-airconnection device of the control pressure 17—with the pressure spaceA—with the connection device of the compressed-air connection to thecontrol chamber 5—. When the valve 19 is open, the pressure space L—withthe connection device for the main air pipe 4—is connected with thepressure space ST.

[0026] A throttle screen 37 is connected into the compressed-airconnection between the control element 30 and the control chamber 50.

[0027]FIG. 4 shows an embodiment according to FIG. 3 with anadditionally inserted venting valve 38 for intensifying the pressurebuild-up and pressure reduction respectively in the brake cylinder pilotchamber 25. The venting valve 38 is connected by way of thecompressed-air connection 39 with the compressed-air connection 24between the control valve and the brake cylinder pilot chamber 25. Inthe open condition, the venting valve 38 connects the brake cylinderpilot chamber 25 and the ambient bore 8. In the closing direction, theventing valve 38 is loaded by the pressure spring 40 and, in the openingdirection, by way of the piston 41 acted upon by control pressure andthe piston rod 42. In the closing direction, the piston 41 is loaded bythe pressure spring 43.

[0028] In the following, the method of operation of the control deviceillustrated in FIGS. 2 and 3 during a braking operation will be brieflydescribed.

[0029] In the ready position of the control valve, the piston rod 6 withthe pistons 3 and 10 is in a lower position, in which the double-seatvalve 14 keeps closed the compressed-air connection of the airconnections 11 and 2 and keeps the brake cylinder pilot chamber 25vented. Since, as a result, the pressure Cv is zero or sufficiently low,the piston 20 is in a lower position because of the effect of thepressure spring 22. The valve 19 and the bypass 32 are open, and themain air pipe 4, the control chamber 5 and the compressed-air connectionof the control pressure 17 are filled to the common normal operatingpressure because the pressure chambers L, ST and A are connected in acompressed-air carrying manner.

[0030] Because of the effect of the control pressure 17 upon the piston16, the valve 15 is opened up so that the main air pipe 4 is connectedwith the compressed-air connection 2, and the pressure from the main airpipe 4 is applied to the double-seat valve 14. In this case, thepressure in the compressed-air connection 2 is determined by thepressure in the main air pipe 4 because this pressure is higher in theready position of the control device than the pressure which would occuronly as a result of the pressure in the supply air reservoir 7 throttledby the valve 13 and the throttle 12 in the compressed-air connection 11or 2. An unintended return flow from the compressed-air connection 2 byway of the compressed-air connection 11 into the supply air reservoircan be avoided by a suitable construction of the valve 13. The pressurein the supply air reservoir can be proportioned such that, after thethrottling by way of the valve 13 and the throttle 12, a constantpressure of, for example, 3.8 bar will occur in the compressed airconnection 11, as long as this pressure is not determined by a higherpressure in the maim air pipe, for example, by 5 bar in the readyposition.

[0031] The method of operation of the braking can be divided into twophases. In phase 1, the pressure in the main air pipe 4 is reduced forthe braking. This reduction may take place slowly, for example, by 0.1bar per second. Since, preferably according to the invention, the bypass32 has a narrow cross-section, the pressure in the pressure chamber Aand thus in the control chamber 5 can follow this pressure reductiononly in a time-delayed manner. This effect can still be reinforced by athrottle screen 37 inserted between the control element 30 and thecontrol chamber 5. As required, a valve can also be inserted there.

[0032] The thus occurring pressure difference at the piston 3 has theresult that the piston rod 6 is moved upward. The piston 10 therebyinterrupts the connection of the brake cylinder pilot chamber 25 to theambient bore 8, and the double-seat valve 14 opens up.

[0033] Now the compressed air flows from the connection 2 into the brakecylinder pilot chamber 25. Because the connection by way of the valve 15to the main air pipe 4 is still open, compressed air flows from the mainair pipe 4 into the brake cylinder pilot chamber 25. The initiation ofthe braking therefore causes a self-intensifying lowering of thepressure in the main air pipe 4.

[0034] As a result of the fact that, at the start of the braking, apressure is provided for filling the brake cylinder pilot chamber 25which is higher than the pressure normally provided by the supply airreservoir 7, in combination with the self-intensifying pressurereduction in the main air pipe 4, a fast propagation of the pneumaticbrake signal from the engine to the end of train end and a uniformbraking force of all cars can be achieved.

[0035] The pressure in the brake cylinder pilot chamber 25 developing inphase 1 causes a movement of the piston 20 against the force of thepressure spring 22. In phase 2, the bypass 32 therefore first slidesover the sliding partition 31. Immediately afterwards, the valve 19closes the connection of the pressures L and ST; simultaneously, thelowering of the pressure ST starts by the flowing-out of compressed airby way of the bore 22 in the piston rod 29.

[0036] After a certain time, the pressure in the chamber ST has droppedso far that the piston 16 is moved downward by means of the pressurespring 18, and the valve 15 separates the main air pipe 4 from thecompressed-air connection 2. As a result, the flowing-over of compressedair from the main air pipe 4 into the brake cylinder pilot chamber 25 isconcluded; the subsequent lowering of the pressure in the main air pipe4 to the full brake application or rapid braking is not furtherintensified by the flowing out of air by way of the valve 15. Since thedouble-seat valve 14 remains open, the pressure in the compressed-airconnections 2 and 11 will drop to the pressure level provided by thesupply air reservoir 7, for example, to 3.8 bar. The filling rate of thebrake cylinder pilot chamber 25 can therefore be adjusted by way of thevalve 13 or the throttle 12 respectively.

[0037] A further lowering of the pressure in the main air pipe to a fullbrake application or a rapid braking, for example, to 3.5 bar or to 0bar, leads to an increase of the pressure difference above the piston 3.As a result of the displacement of the piston rod 6, the double-seatvalve 14 is opened up correspondingly far, and the brake cylinder pilotchamber 25 is filled further.

[0038] By means of the present invention, it therefore becomes possiblefor the first time to provide a control device for compressed-air brakeswhich requires low constructional expenditures and has a small size.When used for automatic brakes, the construction of the describedcontrol device according to the invention results in a high penetrationspeed because of the reaction of the pressure build-up in the brakecylinder or in the brake cylinder pilot chamber on the pressure in themain air pipe and thus in a simultaneous braking effect in all cars. Bymeans of a pressure increase in the brake cylinders which is fast atfirst and then slower, a uniform braking force is achieved for all cars.

List of Reference Numbers

[0039]1 Control valve housing

[0040]2 compressed-air connection

[0041]3 piston

[0042]4 main air pipe

[0043]5 control chamber

[0044]6 piston rod

[0045]7 supply air reservoir

[0046]8 ambient bore

[0047]9 partition

[0048]10 second piston

[0049]11 compressed-air connection

[0050]12 throttle

[0051]13 valve

[0052]14 double-seat valve

[0053]15 valve

[0054]16 piston

[0055]17 control pressure

[0056]18 pressure spring

[0057]19 valve

[0058]20 piston

[0059]21 pressure spring

[0060]22 pressure spring

[0061]23 compressed-air connection to the brake cylinder pilot chamber

[0062]24 compressed-air connection

[0063]25 brake cylinder pilot chamber

[0064]27 pressure spring

[0065]28 sealing device

[0066]29 piston rod

[0067]30 control element

[0068]31 partition

[0069]32 bypass

[0070]33 axial bore

[0071]34 pressure spring

[0072]35 piston rod

[0073]36 second partition

[0074]37 throttle screen

[0075]38 venting valve

[0076]39 compressed-air connection

[0077]40 pressure spring

[0078]41 piston

[0079]42 piston rod

[0080]43 pressure spring

1. Control device for compressed-air brakes 1.1 having a control valve,comprising 1.1.1 a housing (1), 1.1.2 a piston rod (6), 1.1.3 a piston(3), 1.1.4 a second piston (10), 1.1.5 a double-seat valve (14), 1.2having a control element (30), 1.3 having a supply air reservoir (7),1.4 having a control chamber (5), 1.5 having a main air pipe (4), 1.6 aside of the piston (3) being connected with the main air pipe (4) in acompressed-air carrying manner, 1.7 the other side of the piston (3)being connected with the control chamber (5) in a compressed-aircarrying manner, 1.8 one side of the second piston (10) having acompressed-air connection (24) to a brake cylinder or a brake cylinderpilot chamber (25), 1.9 the double-seat valve (14) being connectedbetween a compressed-air connection (11) of the supply air reservoir (7)and the compressed-air connection (24), characterized in that 1.10 acompressed-air connection (2) from the main air pipe (4) to thedouble-seat valve (14) is connected parallel to the compressed-airconnection (11), 1.11 a valve (15) comprising a piston rod (35) and apiston (16) is connected into the compressed-air connection (2), 1.12 onone side, the piston (16) has a compressed-air connection device for acontrol pressure (17), 1.13 on the other side, the piston (16) has adevice for generating a counterforce, particularly a pressure spring(18), 1.14 a control element (30) is connected into the connection pointbetween the main air pipe (4), the control chamber (5), thecompressed-air connection device for the control pressure (17), thebrake cylinder or the brake cylinder pilot chamber (25) and theenvironment.
 2. Device according to claim 1, characterized in that thedouble-seat valve (14) is constructed as a tappet valve loaded in theclosing direction by a pressure spring (27) and in the opening directionby the piston rod (6).
 3. Device according to one of claims 1 to 2,characterized in that the valve (15) is constructed as a tappet valveloaded in the closing direction by a pressure spring (34) and in theopening direction by the piston rod (35).
 4. Device according to one ofclaims 1 to 3, characterized in that the control element (30) comprises4.1 a piston rod (29) having an axial bore (33), 4.2 a piston (20), 4.3a partition (31), 4.4 a second partition (36), 4.5 a valve (19), 4.6 inthe piston rod (29), a bypass (32) for the possible bridging of thepartition (31) being constructed, 4.7 on the side of the piston (20)facing the valve, a compressed-air connection to the brake cylinder orthe brake cylinder pilot chamber (25) being constructed, 4.8 on the sideof the piston (20) facing away from the valve, a device for generating acounterforce, particularly a pressure spring (22), being arranged, 4.9the compressed-air connection device for the control pressure (17) beingconnected by way of the valve (19) with the main air pipe (4), 4.10 thepiston rod leading from the valve (19) through the partition (31) andthe second partition (36) to the piston (20), 4.11 the connection deviceto the compressed-air connection with the control pressure (17) beingconstructed on the side of the partition (31) facing the valve, 4.12 thecompressed-air connection to the control chamber (5) being connected onthe side of the partition (31) facing away from the valve, 4.13 thecompressed-air connection to the brake cylinder or to the brake cylinderpilot chamber being separated by the second partition (36) from thecompressed-air connection to the control chamber (5).
 5. Deviceaccording to claim 4, characterized in that the valve (19) isconstructed as a tappet valve loaded in the closing direction by apressure spring (21) and in the opening direction by the piston rod(29).
 6. Device according to one of claims 1 to 5, characterized in thata valve (13) and/or a throttle screen (12) (37? translator) is connectedinto the compressed-air connection (12).
 7. Device according to one ofclaims 1 to 6, characterized in that the compressed-air connection fromthe main air pipe (4) through the control element (30) to the controlchamber (5) is constructed to have particular pressure losses,particularly by the construction of the bypass (32) with a narrow flowcross-section, so that a pressure drop in the main air pipe (4) takesplace (is followed translator) in a time-delayed manner by a pressuredrop in the control chamber (5).
 8. Device according to one of claims 1to 7, characterized in that a valve and/or a throttle screen (37) isconnected into the compressed-air connection between the control element(30) and the control chamber (5).
 9. Device according to one of claims 1to 8 characterized in that a compressed-air connection (39) with aventing valve (38) is connected between the compressed-air connection(24) and the environment.
 10. Device according to claim 9, characterizedin that the venting valve (38) is constructed as a tappet valve loadedin the opening direction at least indirectly by means of the controlpressure.